We proved that the von-Willebrand-factor A like domain 2 (vWFA2) of Col7 is responsible for type I collagen binding. The interaction has a KD value of 90 ¦ÌM as determined by SPR and is enthalpy driven as derived from the van¡¯t Hoff equation. Furthermore, a hitherto unknown interaction of this domain with type IV collagen was identified. The interaction of vWFA2 with type I collagen is sensitive to the presence of magnesium ions, however, vWFA2 does not contain a magnesium binding site thus magnesium must bind to type I collagen.
A lysine residue has been identified to be crucial for type I collagen binding. This allowed localization of the binding site. Mutational analysis suggests different interaction mechanisms in different species and that these interactions might be of covalent nature.